Embodiments of the inventive concept relate generally to electronic memory technologies. More particularly, embodiments of the inventive concept relate to voltage generators, nonvolatile memory devices, and voltage generating methods.
Semiconductor memory devices can be roughly divided into two categories according to whether they retain stored data when disconnected to power. These categories include volatile memory devices, which lose stored data when disconnected to power, and nonvolatile memory devices, which retain stored data when connected to power.
Volatile memory devices typically have faster read and write performance compared to nonvolatile memory devices, but they are generally not used for long term data storage due to their inability to retain stored data without power. Accordingly, nonvolatile memories are used increasingly to satisfy the ever expanding need for long term data storage.
Among nonvolatile memories, flash memory has achieved widespread popularity due to attractive features such as high integration density, low power consumption, and the ability to withstand physical shock. In addition, researchers continue to develop other types of nonvolatile memories, such as ferroelectric random access memory (FRAM), magnetic RAM (MRAM), phase change random access memory (PRAM), and resistive RAM (RRAM).
Many nonvolatile memory devices require a relatively high voltage for write operations. This high voltage is generally provided through the use of a charge pump. The charge pump, however, can generate a large current, producing noise in the nonvolatile memory devices and deteriorating the reliability of the write operations. Consequently, improved techniques are needed to ensure reliability of the nonvolatile memory devices during generation of the high voltage.